#no-std #kernel #io

nightly no-std cpuio

Bare metal (no_std) inb, outb, inw, outw, inl, outw instructions with Rust-like API

3 releases (breaking)

Uses old Rust 2015

0.3.0 May 20, 2020
0.2.0 Nov 12, 2015
0.1.0 Nov 8, 2015

#964 in Embedded development

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1,204 downloads per month
Used in 4 crates (2 directly)


79 lines

cpuio: Rust wrapper for inb, outb, etc., instructions

WARNING: The interface to the low-level outb, outw and outl functions has changed to match Linux. Please reverse the order of arguments to these three functions.

This library is intended to be run on bare metal, and it only depends on the core library.

To use this, add it to your Cargo.toml file and call cpuio::Port::new to create a port, being sure to specify u8, u16 or u32 depending on the size data supported by the port.

extern crate cpuio;

use cpuio::Port;

fn main() {
    // Create a port pointing at 0x60, the address of the PS/2 keyboard
    // port on x86 hardware.  This is an unsafe operation because many
    // ports can be used to reconfigure your underlying hardware, and
    // it's the responsiblity of the port creator to make sure it's
    // used safely.
    let mut keyboard: Port<u8> = unsafe { Port::new(0x60) };

    // Read a single scancode from a PS/2 keyboard.  If you run this as
    // an ordinary user, it will fail with a SIGSEGV.
    println!("scancode: {}", keyboard.read());

The constructor Port::new is available as a const fn, which allows you to configure a port at compile time.

The is also an UnsafePort type which is identical, except that read and write are explicitly marked as unsafe. It's better to use UnsafePort whenever any individual port operation might corrupt memory or cause undefined behavior.


Licensed under the Apache License, Version 2.0 or the MIT license, at your option.

No runtime deps